LibWeb: Add Crypto.randomUUID()

Author: https://github.com/stelar7
Commit: https://github.com/SerenityOS/serenity/commit/b526a10d76
Pull-request: https://github.com/SerenityOS/serenity/pull/13356
Reviewed-by: https://github.com/skyrising ✅

Userland/Libraries/LibWeb/Crypto/Crypto.cpp

@@ -1,10 +1,12 @@
 /*
  * Copyright (c) 2021, Idan Horowitz <idan.horowitz@serenityos.org>
+ * Copyright (c) 2022, stelar7 <dudedbz@gmail.com>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
 #include <AK/Random.h>
+#include <AK/StringBuilder.h>
 #include <LibJS/Runtime/TypedArray.h>
 #include <LibWeb/Bindings/Wrapper.h>
 #include <LibWeb/Crypto/Crypto.h>
@@ -17,6 +19,7 @@ Crypto::Crypto()
 {
 }
 
+// https://w3c.github.io/webcrypto/#dfn-Crypto-method-getRandomValues
 DOM::ExceptionOr<JS::Value> Crypto::get_random_values(JS::Value array) const
 {
     // 1. If array is not an Int8Array, Uint8Array, Uint8ClampedArray, Int16Array, Uint16Array, Int32Array, Uint32Array, BigInt64Array, or BigUint64Array, then throw a TypeMismatchError and terminate the algorithm.
@@ -40,4 +43,56 @@ DOM::ExceptionOr<JS::Value> Crypto::get_random_values(JS::Value array) const
     return array;
 }
 
+// https://w3c.github.io/webcrypto/#dfn-Crypto-method-randomUUID
+String Crypto::random_uuid() const
+{
+    // 1. Let bytes be a byte sequence of length 16.
+    u8 bytes[16];
+
+    // 2. Fill bytes with cryptographically secure random bytes.
+    fill_with_random(bytes, 16);
+
+    // 3. Set the 4 most significant bits of bytes[6], which represent the UUID version, to 0100.
+    bytes[6] &= ~(1 << 7);
+    bytes[6] |= 1 << 6;
+    bytes[6] &= ~(1 << 5);
+    bytes[6] &= ~(1 << 4);
+
+    // 4. Set the 2 most significant bits of bytes[8], which represent the UUID variant, to 10.
+    bytes[8] |= 1 << 7;
+    bytes[8] &= ~(1 << 6);
+
+    /* 5. Return the string concatenation of 
+        « 
+        hexadecimal representation of bytes[0],
+        hexadecimal representation of bytes[1], 
+        hexadecimal representation of bytes[2],
+        hexadecimal representation of bytes[3],
+        "-", 
+        hexadecimal representation of bytes[4], 
+        hexadecimal representation of bytes[5],
+        "-",
+        hexadecimal representation of bytes[6], 
+        hexadecimal representation of bytes[7],
+        "-",
+        hexadecimal representation of bytes[8], 
+        hexadecimal representation of bytes[9],
+        "-",
+        hexadecimal representation of bytes[10], 
+        hexadecimal representation of bytes[11], 
+        hexadecimal representation of bytes[12], 
+        hexadecimal representation of bytes[13], 
+        hexadecimal representation of bytes[14], 
+        hexadecimal representation of bytes[15]
+        ».
+        */
+    StringBuilder builder;
+    builder.appendff("{:02x}{:02x}{:02x}{:02x}-", bytes[0], bytes[1], bytes[2], bytes[3]);
+    builder.appendff("{:02x}{:02x}-", bytes[4], bytes[5]);
+    builder.appendff("{:02x}{:02x}-", bytes[6], bytes[7]);
+    builder.appendff("{:02x}{:02x}-", bytes[8], bytes[9]);
+    builder.appendff("{:02x}{:02x}{:02x}{:02x}{:02x}{:02x}", bytes[10], bytes[11], bytes[12], bytes[13], bytes[14], bytes[15]);
+    return builder.to_string();
+}
+
 }

Userland/Libraries/LibWeb/Crypto/Crypto.h

@@ -27,6 +27,7 @@ public:
     NonnullRefPtr<SubtleCrypto> subtle() const { return m_subtle; }
 
     DOM::ExceptionOr<JS::Value> get_random_values(JS::Value array) const;
+    String random_uuid() const;
 
 private:
     Crypto();

Userland/Libraries/LibWeb/Crypto/Crypto.idl

@@ -6,4 +6,6 @@ interface Crypto {
 
   // FIXME: the argument and the return value should be of type ArrayBufferView
   any getRandomValues(any array);
+
+  [SecureContext] DOMString randomUUID();
 };